1. Field of the Invention
The present invention relates to a monitoring system and method for monitoring a clean room regulating system. More particularly, the monitoring system determines the operational state of the regulating system by transferring signals from the regulating system through an interface to a host computer.
2. Description of the Related Art
High-tech industries including the electronics industry require a clean, consistently maintained fabrication environment which meets certain cleanliness criteria. Most of the fabrication processes of highly-integrated semiconductor devices are carried out in such "clean rooms." Clean room conditions, including temperature, humidity, air flow rate, pressure difference and particle distributions, can greatly affect the yield of semiconductor device production. Therefore, air quality in a clean room should be regularly checked to ensure that cleanliness criteria in terms of number of particles per unit volume are being met. Other air quality parameters such as air temperature, humidity, flow rate, and pressure also should be checked by a regulating system. Such a system therefore includes sensors for detecting the temperature and humidity of air in the clean room, a sensor for detecting the flow rate of air, a sensor for sensing the pressure difference between the inside and outside of the clean room, and a set of particle counters for checking the particle content in several sample volumes of air from which the distribution of particles inside the clean room can be inferred. Accordingly, these conditions are monitored using the above sensors.
However, such precise monitoring cannot be performed when any of the sensors of the regulating system, especially a particle counter, is not operating normally. Therefore, the sensors, especially the particle counters, should be periodically checked. This is usually done by a check performed at the site of the sensor. Because periodic checking at the site is difficult, it is often not performed until after the sensor has been operating in an abnormal state for some time. As a result, much of the data monitored from the regulating system is unreliable for the time period between the last periodic check and the discovery of an abnormally operating sensor.
Accordingly, there is a need for a more efficient means of monitoring both a clean room maintained by a regulating system and the sensors of the regulating system itself.